Current communication systems that switch according to the time division multiplex method, in particular private narrowband telephone switching equipment, are connected with one another via individual narrowband fixed connections or narrowband line bundles. Narrowband connections represent in particular pulse-code modulated (PCM) connections, that is, digitized telephone connections or data connections with a transmission speed of up to 64 kbit/s. Line bundles are formed through multiplexing of the message and signaling information of several narrowband connections, whereby standardized line bundles comprise 32 or 24 narrowband connections or, respectively, channels, and a transmission speed of 2048 kbit/s or 1544 kbit/s. The individual narrowband connections or line bundles provided between the communication systems are switched via fixed connections provided by public or private network operators.
In the future, communication networks operating according to the asynchronous transfer mode (known to those skilled in the art as ATM communication networks) are provided for the switching or, respectively, transmission of the message and signaling information of line bundles in particular. For this purpose, it has been proposed in the relevant standardization committee (ATM Forum) to switch the message and signaling information of line bundles via virtual fixed connections of an ATM communication network. According to this standard "Circuit Emulation Service (CES)," the combined 64 kbit/s message channels, including the signaling channel (that is, the multiplexed channels with a transmission speed of 2048 kbit/s), are transmitted cell by cell via a permanent virtual connections, that is, fixed connection of an ATM communication network. The transmission of the signaling and message information via the ATM communication network ensues transparently, that is, in relation to the standardized protocol layers, the signaling and message information are transmitted transparently according to layers 2 and 3. Since the virtual fixed connections are to be set up administratively, that is, via network management installations through the input of corresponding operation and maintenance instructions, an adaptation to a different number of line bundles to be transmitted, caused by different volumes of traffic within a day or a week, is costly with respect to personnel and time. The size or, respectively, the number of line bundles is hereby to be matched to a peak traffic time, whereby the number of line bundles between the time division multiplex-designed communication systems is determined by this maximum. This means a maximal consumption of resources in the respective ATM communication network, as well as maximum costs for the switching of the line bundles.